Thank you! Decided to pass on Fixdry and get a kitchen dehydrator Graef
I found this. because we are on this topic, maybe can give some though if this unit is really usefull. the spec I found is that this is for fruit dehydrator:
Capacity: 3 KG
Control method: mechanic
electricity: 220V
power: 345W
Frekuenzie: 50-60HZ
Body material: PP/PS
capacity: 5 level
heat method: heated with heating element
heating level: 8 level
product size: 280280320mm.
is this a good one to choose for filament dehydrator? cheapest one I can buy…
I apologize it’s not posted yet, but if you want to check out “Filament drying preliminary results”, if that’s something you would be interested in, it won’t work with a food dehydrator. You need a regular filament dryer that is mostly closed up like a Sunlu S2 for example if you want to supercharge filament drying by pumping dry air into the filament dryer.
Dehydrators have fans that circulate outside air in and out of the dehydrator but outside air can have lots of humidity. That humidity limits how much you can dry filament and how fast. Most filament dryers don’t work well because they trap moisture inside them, but that works great with a dry air supply that pushes out the moist air. It turns a problem into an asset.
^^^Yes, for anyone who hasn’t yet looked, MZip has done absolutely fantastic work, and his thread is well worth reading. Already, the objective evidence he has compiled for his method looks very compelling.
Do you have a special container of some kind for holding the desiccant as you dry it in your S4?
Yeah, printed a basket off of Makerworld. Nothing fancy
What looks especially promising about the S4 is the rated power of 320w and the three fans to really stir up the air, hopefully helping to get to a better temperature uniformity. A surprisingly high number of filament dryers have only 50w heaters and may lack even one circulation fan. The main shortcoming seems to be the max temp of 70C, which blunts its potential capability, but that’s still enough headroom for some of the common filaments, assuming its sensors are accurate and it’s not also lying about the temperature, like some filament dryers do, by poor sensor placement, which results in reporting a higher temperature than what’s representative of the true situation.
I ordered one to supplement my other filament drying, letting me speed up my drying by helping to do more in parallel and/or pipelining. It should arrive today, so I guess we’ll see. The reviews seem generally favorable. If it’s not too loud, I may be able to run it in the conditioned space and thereby leverage the dryer air inside the house. Like Aurora Tech said, it would be nice if it were more user programmable, but that’s consumer products for you.
I have to say for the most part it’s been transparent for me. I drop what I want to dry the day before and go on about my business. I have it set to maintain I think 35 rh, but I could be wrong, as far down as it goes. I hear it come on once in awhile.
If I need something dried somewhat quickly I’ll set it for that and about 8 hours. PA-6 and TPU95-HF I keep in there and feed from it. Works well. Usually just store ABS and the like until needed.
I bought a Sunlu S4 because 1 S4 is more cost effective.
I have not yet plumbed it up to printer yet but it sure made a big difference in the number of dimples on the printed object. Didn’t entirely eliminate them but it was a major improvement.
I had made the desiccant bead holders that go between each of the drives in the AMS with an RH indicator in the center slot.
On a whim because that center desiccant in AMS Was reading around 30% I pulled it out and put in bottom of S4.
Checked it the next day and it was reading 10% so put it back in AMS.
Somewhat question the ability of AMS to do anything significant to moisture, even with desiccant in the lower locations and those in the front of the AMS.
There is very little air mmovement in the AMS. The filament towards the center of a given spool sees zero circulation.
I think my practice going forward will be to put spools in and out of S4 based on when I’m going to use them
Well, don’t forget that your spools of filament, if you load them dry into the AMS, are themselves acting like a kind of desiccant, in that they absorb moisture from the air. So, if you’re just reading a TH sensor and watching it only slowly climb up, maybe the rate of moisture intrusion is actually worse than you think.
I did an experiment recently where I pumped relatively dry air into one of the cereal containers commonly used on this forum for filament storage. I put a TH sensor in it with no desiccnat or anything else. It returned to ambient humidity in about 4 days. From that I calculated the amount of moisture that actually penetrated, and posted it somewhere on the forum here. It turns to out not to have been much. You could do the same or similar with the AMS, and then maybe you’d have a better way of knowing for sure. You’d need to know the air volume of the AMS, or a reasonable approximation, to run the calculation though.
First off, what’s a TH Sensor and if TH is Temperature/Humidity, what brand and type of sensor is it.
I put a set of the desiccant containers off of Printables.com in my AMS. The type that slide in between each feeder. I don’t think they do much as they sit in a dead zone as far as air flow. The whole purpose of a desiccant container is wet air in, dry air out.
No airflow through desiccant = no drying. The reason they are beads is because you maximize airflow across the surface area of each bead without significantly increasing resistance to that airflow. It falls in the category of a Tortuous Pathway through the beads.
Anyone want to count the number of beads in one of these baskets, then calculate the surface area of a bead, multiply the two and get how many square inches of that equates to?
Now, get 2 - 3 ft of 10" PVC pipe, put threaded end caps on it, fill with desiccant and use an aquarium air compressor to blow your ambient air in on one end, and let that bone dry air coming out the other end keep the AMS under a slight positive pressure…
It has to go through the media. The media isn’t acting like a magnet but for water molecules.
That’s amazing. Now I know how Dom Cobb felt in the movie Inception. 
Get the color changing dessicant and then see how much they absorb. I think you’ll lbe surprised.
Well what I mean is you’ll see that it absorbs moisture within the AMS.
Does it make a huge difference? I’m not so sure, but it does absorb. I have been back and forth a few times on taking them out, but in the end it doen’t hurt.
(I see MZip replying…so you’ll know soon)
I suspect a fair amount of that is from opening the hood, swapping spools.
Like you say, it’s already made and installed so no loss even if it is just a small incremental improvement.
I think I may go ahead and build what I described. I now have enough PVC cement to glue 10,000 multi-part prints together per my glue question. Lowe’s and two pet stores 10 minutes away. Give me something to do while waiting on a multi-hour print to complete.
I bought a second AMS hood already because…why not.
A few things here in no particular order but to maybe clear up some misconceptions? It’s not “dead air” when you look at molecular motion. At room temperature the average water vapor molecule is moving 18.8 m/s, or about 42 miles per hour. The mean free path at standard temperature and pressure is about 68nm. There’s all sorts of hitting, banging, and movement going on.
And there is still convection happening in a filament dryer. There are some cool IR videos of air or other fluids being heated by a surface and the hot fluid streaming up from density changes - like a hot air balloon does or the density changes visualize in a pot of water that is heating on the stove.
The filament dryers with fans may even slow down drying by keeping the air stirred up inside the chamber. Any air exchange with the outside air is with “average” fan-stirred air inside the chamber. Ideally, you’d want to somehow let out the humid air and keep the driest air in the filament dryer to help speed drying. If only there was a way…
Humid air is less dense than dry air and rises. My S2+ has a fan at the bottom and filament exit holes/vents near the top of the chamber. Just letting the humid air rise in the “dead air” of the chamber gets it to the vents and out of the chamber faster than keeping the air homogeneous with a fan. Combined with a dry air purge introduced at the bottom of the chamber, there’s a lucky stratification that helps get water out more effectively.
I haven’t tested disconnecting the fan yet to let that stratification help drying to know how much it will help but it should help.
As to surface area of a silica gel bead, it’s reportedly about 700-800 m^2/gram - way more than the equation for surface area of a sphere would suggest.
And @NeverDie made an important point above - in the AMS a spool of dry filament is just as much a desiccant as the desiccant is. Everybody is in the fight for water game either as a source or a sink and which they are just depends on where they are on an RH/moisture content graph. And those graphs also explain why measuring spool humidity in a poly cereal box with a hygrometer works as an indicator of filament moisture content - the humidity is related to moisture content which is why those curves can even exist. There is a relationship. Not linear, different for various materials, but repeatable and monotonic which means the test can be used as a go/no go test.
I’m an Entropy guy myself.
But if I want to improve the Brownian motion in my AMS, I’d put a little 12V computer fan along the long axis of the spools to juice the water molecules, most of which are trapped 2, 3, 4, 8 coils deep so don’t bounce around at all. Not much motion of a water molecule trapped in a filament strand.
Just be mindful that the RH% inside your home is significantly lower (in summer) than the weather report value.
That’s why (depending on your individual AC setup) your evaporator coil has to have a drip pan and why it is good practice to make sure the drain line doesn’t get plugged.